Wikipedia

Xylocopa varipuncta

The Valley carpenter bee, Xylocopa varipuncta, is one of three species of carpenter bee found in Southern California and north through the Central Valley and in Phoenix, Az. Females are a metallic black while males are fuzzy and gold with green eyes. They are the largest bees found in California,[1] growing to around 1 in (2.5 cm) in length.

The size of carpenter bees prevents them from entering tubelike flowers, instead they cut into the base of the corolla. This is referred to as “stealing the nectar” as it does not result in the bee being able to pollinate the flower.[3] They are helpful in pollinating native plants and shrubs.

The bees tunnel through wood with their mandibles, although they do not ingest the wood in the process. The tunnels average 6 to 10 in (15 to 25 cm) in length and consist of a linear series of partitioned cells.[1][3] They prefer untreated or unpainted wood. The adult bees spend the winter in the tunnels.